Researchers discovered goldfish weighing 4 pounds in the waterways of Western Australia. (Murdoch University)

We know invasive species can be a real issue for local ecosystems, but did you ever think that one of the most common pets across North America could be the culprit? Your goldfish might be tiny, but a recent study shows that given the opportunity, Goldie can grow to be the size of a football.

If you've ever thought about putting your goldfish back in its wild home, or flushing it down a porcelain path, think twice. You may think it's humane, but it's actually detrimental for the environment.

“Once established, self-sustaining populations of alien freshwater fishes often thrive and can spread into new regions, which is and are major drivers of the decline of aquatic fauna,” Stephen Beatty, a lead researcher studying goldfish and their movement, said in a press release.

Beatty and a team of researchers from Murdoch University have been studying the introduction of goldfish into freshwater bodies in Western Australia and the impacts that those little fish can have on the ecosystem. When aquariums and pet owners dump their fish back into the water, it can introduce diseases, harm native species, impact water quality, and can be disruptive to the habitat as a whole, he said.

The researchers, whose study has been published in the international journal Ecology of Freshwater Fish, found that the , and the fish can travel more than 140 miles within the freshwater system in a single year.

They may start out tiny, but give these fish room to grow and they will. (Rebecca Baldwin/Alberta Environment and Parks)

These goldfish are becoming a real issue across the globe as they are returned to much larger bodies of water than your average fish tank. In the past year at Edgewater Pond in St. Albert, droves of goldfish have been taking over the ecosystem.In Minnesota, officials warned that goldfish showing up in lakes there were found .

According to Ontario's Invading Species Awareness Program,by competing with native species and becoming a main predator of a variety of flora and fauna.

"They stir up mud and other matter when they feed, which increases the cloudiness of the water and affects the growth of aquatic plants," their website reads.

On top of that, they can reproduce quickly and are often very difficult to catch and kill. Officials tried electro-fishing them and , the St. Albert Gazette reports, but the fish survived even through the frigid Canadian winter.

This wouldn't be a major concern if the problem was contained within the storm water pond, buthere's no way to prevent the fish from making their way into the streams and lakes in the larger ecosystem.

Flushing is just as bad, even if you are certain your fish is dead.

"Even if the fish are dead, they could have diseases or parasites that could be introduced,","especially if the water treatment system is not top notch."